If you have an employer that would fire someone for saying "I don't feel I can do this job in a safe manner" then they aren't really worth working for.
Just my opinion.
Yep, well, that's the way a lot of places are. The offshore oilfield got so bad with the "You do it or I'll send your relief!" threats on captain's jobs from management when captains would refuse to do stupid dangerous stuff at the demand of the Company Man that Louisiana enacted (and enforces) a law that holds management Criminally liable for any accidents that occur after they threaten the captain's job. This went a long way to making the GoM a safer place to work.